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          2013 Multi-University Training Contest 1
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        <p><a target="_blank" rel="noopener" href="http://acm.hdu.edu.cn/showproblem.php?pid=4600">4600 Harvest Moon</a> 待补 <span id="more"></span> <a target="_blank" rel="noopener" href="http://acm.hdu.edu.cn/showproblem.php?pid=4601">4601 Letter Tree</a> 待补</p>
<p><a target="_blank" rel="noopener" href="http://acm.hdu.edu.cn/showproblem.php?pid=4602">4602 Partition</a> OEIS一波即可 交的时候错了两次，是因为没有判断<span class="math inline">\(N \le K\)</span>的情况</p>
<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">typedef</span> <span class="keyword">long</span> <span class="keyword">long</span> LL;</span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="keyword">const</span> LL mod=<span class="number">1e9</span>+<span class="number">7</span>;</span><br><span class="line"><span class="function">LL <span class="title">kpow</span><span class="params">(LL t,<span class="keyword">int</span> x)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">if</span>(x==<span class="number">0</span>) <span class="keyword">return</span> <span class="number">1</span>;</span><br><span class="line">	LL o=<span class="built_in">kpow</span>(t,x/<span class="number">2</span>);</span><br><span class="line">	o*=o;</span><br><span class="line">	o%=mod;</span><br><span class="line">	<span class="keyword">if</span>(x&amp;<span class="number">1</span>) o*=t;</span><br><span class="line">	o%=mod;</span><br><span class="line">	<span class="keyword">return</span> o;</span><br><span class="line">&#125;</span><br><span class="line"><span class="function">LL <span class="title">ff</span><span class="params">(LL x)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">if</span>(x==<span class="number">0</span>) <span class="keyword">return</span> <span class="number">1</span>;</span><br><span class="line">	LL ans=x+<span class="number">2</span>;</span><br><span class="line">	ans*=<span class="built_in">kpow</span>(<span class="number">2</span>,x<span class="number">-1</span>);</span><br><span class="line">	ans%=mod;</span><br><span class="line">	<span class="keyword">return</span> ans;</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">work</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	LL n,k;</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%lld%lld&quot;</span>,&amp;n,&amp;k);</span><br><span class="line">	n-=k;</span><br><span class="line">	<span class="keyword">if</span>(n==<span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;1\n&quot;</span>);</span><br><span class="line">		<span class="keyword">return</span>;</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">if</span>(n&lt;<span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;0\n&quot;</span>);</span><br><span class="line">		<span class="keyword">return</span>;</span><br><span class="line">	&#125;</span><br><span class="line">	LL ans=<span class="built_in">ff</span>(n<span class="number">-1</span>)+<span class="built_in">kpow</span>(<span class="number">2</span>,n<span class="number">-1</span>);</span><br><span class="line">	ans%=mod;</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;%lld\n&quot;</span>,ans);</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">int</span> T;</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;T);</span><br><span class="line">	<span class="keyword">while</span>(T--) <span class="built_in">work</span>();</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p><a target="_blank" rel="noopener" href="http://acm.hdu.edu.cn/showproblem.php?pid=4603">4603 Color the Tree</a> 待补</p>
<p><a target="_blank" rel="noopener" href="http://acm.hdu.edu.cn/showproblem.php?pid=4604">4604 Deque</a> 可以看出是某个数字开头的最长不上升子序列和最长不下降子序列拼在一起形成的。 要注意判断两个序列重合的部分，要把重合的部分删去。 错了好多次，都是二分条件的问题...这个二分好难写啊...</p>
<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> pb push_back</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="keyword">int</span> n;</span><br><span class="line"><span class="keyword">int</span> a[<span class="number">100010</span>];</span><br><span class="line">vector&lt;<span class="keyword">int</span>&gt; x;</span><br><span class="line">vector&lt;<span class="keyword">int</span>&gt; y;</span><br><span class="line"><span class="keyword">int</span> ans;</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">work</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;n);</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i&lt;=n;i++)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;a[i]);</span><br><span class="line">	&#125;</span><br><span class="line">	x.<span class="built_in">clear</span>(); y.<span class="built_in">clear</span>();</span><br><span class="line">	x.<span class="built_in">pb</span>(a[n]); y.<span class="built_in">pb</span>(-a[n]);</span><br><span class="line">	ans=<span class="number">1</span>;</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=n<span class="number">-1</span>;i&gt;=<span class="number">1</span>;i--)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="keyword">int</span> l,r;</span><br><span class="line">		l=<span class="number">0</span>; r=x.<span class="built_in">size</span>()<span class="number">-1</span>;</span><br><span class="line">		<span class="keyword">while</span>(l&lt;r)</span><br><span class="line">		&#123;</span><br><span class="line">			<span class="keyword">int</span> mid=(l+r)/<span class="number">2</span>;</span><br><span class="line">			<span class="keyword">if</span>(x[mid]&gt;=a[i]) r=mid;</span><br><span class="line">			<span class="keyword">else</span> l=mid+<span class="number">1</span>;</span><br><span class="line">		&#125;</span><br><span class="line">		<span class="keyword">int</span> zz=l;</span><br><span class="line">		l=<span class="number">0</span>; r=x.<span class="built_in">size</span>()<span class="number">-1</span>;</span><br><span class="line">		<span class="keyword">while</span>(l&lt;r)</span><br><span class="line">		&#123;</span><br><span class="line">			<span class="keyword">int</span> mid=(l+r)/<span class="number">2</span>+<span class="number">1</span>;</span><br><span class="line">			<span class="keyword">if</span>(x[mid]&lt;=a[i]) l=mid;</span><br><span class="line">			<span class="keyword">else</span> r=mid<span class="number">-1</span>;</span><br><span class="line">		&#125;</span><br><span class="line">		<span class="keyword">int</span> yy=r; <span class="keyword">if</span>(x[yy]&lt;=a[i]) yy++;</span><br><span class="line">		<span class="keyword">if</span>(yy==x.<span class="built_in">size</span>()) x.<span class="built_in">pb</span>(a[i]);</span><br><span class="line">		<span class="keyword">else</span> x[yy]=a[i];</span><br><span class="line">		<span class="keyword">int</span> len1=yy+<span class="number">1</span>;</span><br><span class="line">		<span class="keyword">int</span> sa=yy-zz+<span class="number">1</span>;</span><br><span class="line">		l=<span class="number">0</span>; r=y.<span class="built_in">size</span>()<span class="number">-1</span>;</span><br><span class="line">		<span class="keyword">while</span>(l&lt;r)</span><br><span class="line">		&#123;</span><br><span class="line">			<span class="keyword">int</span> mid=(l+r)/<span class="number">2</span>;</span><br><span class="line">			<span class="keyword">if</span>(y[mid]&gt;=-a[i]) r=mid;</span><br><span class="line">			<span class="keyword">else</span> l=mid+<span class="number">1</span>;</span><br><span class="line">		&#125;</span><br><span class="line">		zz=l;</span><br><span class="line">		l=<span class="number">0</span>; r=y.<span class="built_in">size</span>()<span class="number">-1</span>;</span><br><span class="line">		<span class="keyword">while</span>(l&lt;r)</span><br><span class="line">		&#123;</span><br><span class="line">			<span class="keyword">int</span> mid=(l+r)/<span class="number">2</span>+<span class="number">1</span>;</span><br><span class="line">			<span class="keyword">if</span>(y[mid]&lt;=-a[i]) l=mid;</span><br><span class="line">			<span class="keyword">else</span> r=mid<span class="number">-1</span>;</span><br><span class="line">		&#125;</span><br><span class="line">		yy=r; <span class="keyword">if</span>(y[yy]&lt;=-a[i]) yy++;</span><br><span class="line">		<span class="keyword">if</span>(yy==y.<span class="built_in">size</span>()) y.<span class="built_in">pb</span>(-a[i]);</span><br><span class="line">		<span class="keyword">else</span> y[yy]=-a[i];</span><br><span class="line">		<span class="keyword">int</span> len2=yy+<span class="number">1</span>;</span><br><span class="line">		sa=<span class="built_in">min</span>(sa,yy-zz+<span class="number">1</span>);</span><br><span class="line">		ans=<span class="built_in">max</span>(ans,len1+len2-sa);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;%d\n&quot;</span>,ans);</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">int</span> T;</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;T);</span><br><span class="line">	<span class="keyword">while</span>(T--) <span class="built_in">work</span>();</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p><a target="_blank" rel="noopener" href="http://acm.hdu.edu.cn/showproblem.php?pid=4605">4605 Magic Ball Game</a> 把所有的询问离线到固定的点上，然后用最简单的可持久化方法，在树上爬，然后用树状数组维护向左的边对应的值、向右的边对应的值，如果这个点上有询问，那就查询一下，计算出相对应的概率就可以了。</p>
<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span 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class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br><span class="line">105</span><br><span class="line">106</span><br><span class="line">107</span><br><span class="line">108</span><br><span class="line">109</span><br><span class="line">110</span><br><span class="line">111</span><br><span class="line">112</span><br><span class="line">113</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> pb push_back</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">BITree</span>&#123;</span></span><br><span class="line"><span class="keyword">public</span>:</span><br><span class="line">    <span class="keyword">static</span> <span class="keyword">const</span> <span class="keyword">int</span> SIZE = <span class="number">300010</span>, BIAS = <span class="number">5</span>;</span><br><span class="line">    <span class="keyword">long</span> <span class="keyword">long</span> u[SIZE];</span><br><span class="line">    <span class="function"><span class="keyword">void</span> <span class="title">clear</span><span class="params">()</span></span>&#123;</span><br><span class="line">        <span class="built_in">memset</span>(u,<span class="number">0</span>,<span class="built_in"><span class="keyword">sizeof</span></span>(u));</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="function"><span class="keyword">void</span> <span class="title">modify</span><span class="params">(<span class="keyword">int</span> x, <span class="keyword">long</span> <span class="keyword">long</span> v)</span></span>&#123;</span><br><span class="line">        <span class="keyword">for</span>(x+=BIAS;x&lt;SIZE;x+=x&amp;-x) u[x]+=v;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="function"><span class="keyword">long</span> <span class="keyword">long</span> <span class="title">getsum</span><span class="params">(<span class="keyword">int</span> x)</span></span>&#123;</span><br><span class="line">        <span class="keyword">long</span> <span class="keyword">long</span> s=<span class="number">0</span>;</span><br><span class="line">        <span class="keyword">for</span>(x+=BIAS;x;x-=x&amp;-x) s+=u[x];</span><br><span class="line">        <span class="keyword">return</span> s;</span><br><span class="line">    &#125;</span><br><span class="line">&#125; trl,trr;  </span><br><span class="line"><span class="keyword">int</span> n,m;</span><br><span class="line"><span class="keyword">int</span> e[<span class="number">100010</span>][<span class="number">2</span>];</span><br><span class="line"><span class="keyword">int</span> w[<span class="number">100010</span>];</span><br><span class="line"><span class="keyword">int</span> Q;</span><br><span class="line">vector&lt;<span class="keyword">int</span>&gt; q[<span class="number">100010</span>];</span><br><span class="line">vector&lt;<span class="keyword">int</span>&gt; id[<span class="number">100010</span>];</span><br><span class="line"><span class="keyword">int</span> ans1[<span class="number">100010</span>];</span><br><span class="line"><span class="keyword">int</span> ans2[<span class="number">100010</span>];</span><br><span class="line">vector&lt;<span class="keyword">int</span>&gt; t;</span><br><span class="line">map&lt;<span class="keyword">int</span>,<span class="keyword">int</span>&gt; ha;</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">dfs</span><span class="params">(<span class="keyword">int</span> x,<span class="keyword">int</span> fa,<span class="keyword">int</span> wi)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i&lt;q[x].<span class="built_in">size</span>();i++)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="keyword">int</span> p=ha[q[x][i]];</span><br><span class="line">		<span class="keyword">int</span> u=id[x][i];</span><br><span class="line">		<span class="keyword">int</span> bj=trl.<span class="built_in">getsum</span>(p)-trl.<span class="built_in">getsum</span>(p<span class="number">-1</span>)+trr.<span class="built_in">getsum</span>(p)-trr.<span class="built_in">getsum</span>(p<span class="number">-1</span>);</span><br><span class="line">		<span class="keyword">if</span>(bj!=<span class="number">0</span>) ans1[u]=<span class="number">0</span>,ans2[u]=<span class="number">-1</span>;</span><br><span class="line">		<span class="keyword">else</span></span><br><span class="line">		&#123;</span><br><span class="line">			ans2[u]+=trl.<span class="built_in">getsum</span>(p)*<span class="number">3</span>;</span><br><span class="line">			ans2[u]+=(trl.<span class="built_in">getsum</span>(<span class="number">200001</span>)-trl.<span class="built_in">getsum</span>(p));</span><br><span class="line">			ans2[u]+=trr.<span class="built_in">getsum</span>(p)*<span class="number">3</span>;</span><br><span class="line">			ans2[u]+=(trr.<span class="built_in">getsum</span>(<span class="number">200001</span>)-trr.<span class="built_in">getsum</span>(p));</span><br><span class="line">			ans1[u]+=trr.<span class="built_in">getsum</span>(p);</span><br><span class="line">		&#125;</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">if</span>(e[x][<span class="number">0</span>]!=<span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		trl.<span class="built_in">modify</span>(ha[w[x]],<span class="number">1</span>);</span><br><span class="line">		<span class="built_in">dfs</span>(e[x][<span class="number">0</span>],x,<span class="number">0</span>);</span><br><span class="line">		trr.<span class="built_in">modify</span>(ha[w[x]],<span class="number">1</span>);</span><br><span class="line">		<span class="built_in">dfs</span>(e[x][<span class="number">1</span>],x,<span class="number">1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">if</span>(fa!=<span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="keyword">if</span>(wi==<span class="number">0</span>) trl.<span class="built_in">modify</span>(ha[w[fa]],<span class="number">-1</span>);</span><br><span class="line">		<span class="keyword">if</span>(wi==<span class="number">1</span>) trr.<span class="built_in">modify</span>(ha[w[fa]],<span class="number">-1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">return</span>;</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">work</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	ha.<span class="built_in">clear</span>();</span><br><span class="line">	t.<span class="built_in">clear</span>();</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;n);</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i&lt;=n;i++)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;w[i]);</span><br><span class="line">		t.<span class="built_in">pb</span>(w[i]); e[i][<span class="number">0</span>]=e[i][<span class="number">1</span>]=<span class="number">0</span>;</span><br><span class="line">		q[i].<span class="built_in">clear</span>();</span><br><span class="line">		id[i].<span class="built_in">clear</span>();</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;m);</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i&lt;=m;i++)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="keyword">int</span> u,a,b;</span><br><span class="line">		<span class="built_in">scanf</span>(<span class="string">&quot;%d%d%d&quot;</span>,&amp;u,&amp;a,&amp;b);</span><br><span class="line">		e[u][<span class="number">0</span>]=a; e[u][<span class="number">1</span>]=b;</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;Q);</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i&lt;=Q;i++)</span><br><span class="line">	&#123;</span><br><span class="line">		ans1[i]=<span class="number">0</span>;</span><br><span class="line">		ans2[i]=<span class="number">0</span>;</span><br><span class="line">		<span class="keyword">int</span> v,x;</span><br><span class="line">		<span class="built_in">scanf</span>(<span class="string">&quot;%d%d&quot;</span>,&amp;v,&amp;x);</span><br><span class="line">		q[v].<span class="built_in">pb</span>(x);</span><br><span class="line">		t.<span class="built_in">pb</span>(x);</span><br><span class="line">		id[v].<span class="built_in">pb</span>(i);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="built_in">sort</span>(t.<span class="built_in">begin</span>(),t.<span class="built_in">end</span>());</span><br><span class="line">	<span class="keyword">int</span> num=<span class="number">0</span>;</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">auto</span> &amp;i:t)</span><br><span class="line">	&#123;</span><br><span class="line">		num++;</span><br><span class="line">		ha[i]=num;</span><br><span class="line">	&#125;</span><br><span class="line">	trl.<span class="built_in">clear</span>();</span><br><span class="line">	trr.<span class="built_in">clear</span>();</span><br><span class="line">	<span class="built_in">dfs</span>(<span class="number">1</span>,<span class="number">0</span>,<span class="number">-1</span>);</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i&lt;=Q;i++)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="keyword">if</span>(ans2[i]==<span class="number">-1</span>) <span class="built_in">printf</span>(<span class="string">&quot;%d\n&quot;</span>,ans1[i]);</span><br><span class="line">		<span class="keyword">else</span> <span class="built_in">printf</span>(<span class="string">&quot;%d %d\n&quot;</span>,ans1[i],ans2[i]);</span><br><span class="line">	&#125;</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">int</span> T;</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;T);</span><br><span class="line">	<span class="keyword">while</span>(T--) <span class="built_in">work</span>();</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p><a target="_blank" rel="noopener" href="http://acm.hdu.edu.cn/showproblem.php?pid=4606">4606 Occupy Cities</a> 几何题...不想做...</p>
<p><a target="_blank" rel="noopener" href="http://acm.hdu.edu.cn/showproblem.php?pid=4607">4607 Park Visit</a> 求出树的直径，然后如果要访问的点的个数<span class="math inline">\(\le\)</span>直径上的点个数的话，那对应的边走一次就行。如果要访问的点的个数<span class="math inline">\(\ge\)</span>直径上的点的个数，那多出的点每个点要走两条边才能走到。</p>
<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> N 100010</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> pb push_back</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line">vector&lt;<span class="keyword">int</span>&gt; e[N];</span><br><span class="line"><span class="keyword">int</span> d[N];</span><br><span class="line"><span class="keyword">int</span> n,m;</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">ff</span><span class="params">(<span class="keyword">int</span> x,<span class="keyword">int</span> fa)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	d[x]=d[fa]+<span class="number">1</span>;</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">auto</span> &amp;i:e[x])</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="keyword">if</span>(i!=fa) <span class="built_in">ff</span>(i,x);</span><br><span class="line">	&#125;</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">work</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d%d&quot;</span>,&amp;n,&amp;m);</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i&lt;=n;i++) e[i].<span class="built_in">clear</span>(),d[i]=<span class="number">0</span>;</span><br><span class="line">	<span class="keyword">int</span> a,b;</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i&lt;n;i++)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">scanf</span>(<span class="string">&quot;%d%d&quot;</span>,&amp;a,&amp;b);</span><br><span class="line">		e[a].<span class="built_in">pb</span>(b);</span><br><span class="line">		e[b].<span class="built_in">pb</span>(a);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="built_in">ff</span>(<span class="number">1</span>,<span class="number">0</span>);</span><br><span class="line">	<span class="keyword">int</span> s=<span class="number">0</span>;</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i&lt;=n;i++) <span class="keyword">if</span>(d[i]&gt;d[s]) s=i;</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i&lt;=n;i++) d[i]=<span class="number">0</span>;</span><br><span class="line">	<span class="built_in">ff</span>(s,<span class="number">0</span>);</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i&lt;=n;i++) <span class="keyword">if</span>(d[i]&gt;d[s]) s=i;</span><br><span class="line">	<span class="keyword">int</span> ans=d[s];</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i&lt;=m;i++)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;a);</span><br><span class="line">		<span class="keyword">if</span>(a&lt;=ans) <span class="built_in">printf</span>(<span class="string">&quot;%d\n&quot;</span>,a<span class="number">-1</span>);</span><br><span class="line">		<span class="keyword">else</span> <span class="built_in">printf</span>(<span class="string">&quot;%d\n&quot;</span>,ans<span class="number">-1</span>+(a-ans)*<span class="number">2</span>);</span><br><span class="line">	&#125;</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">int</span> T;</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;T);</span><br><span class="line">	<span class="keyword">while</span>(T--) <span class="built_in">work</span>();</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p><a target="_blank" rel="noopener" href="http://acm.hdu.edu.cn/showproblem.php?pid=4608">4608 I-number</a> 简单题，暴力爬一爬就行</p>
<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="keyword">char</span> c[<span class="number">100010</span>];</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">work</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%s&quot;</span>,c+<span class="number">1</span>);</span><br><span class="line">	<span class="keyword">int</span> n=<span class="built_in">strlen</span>(c+<span class="number">1</span>);</span><br><span class="line">	c[<span class="number">0</span>]=<span class="string">&#x27;0&#x27;</span>;</span><br><span class="line">	<span class="keyword">int</span> u=<span class="number">1</span>;</span><br><span class="line">	<span class="keyword">while</span>(u%<span class="number">10</span>!=<span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		u=<span class="number">0</span>;</span><br><span class="line">		c[n]++;</span><br><span class="line">		<span class="keyword">int</span> p=n;</span><br><span class="line">		<span class="keyword">while</span>(c[p]&gt;<span class="string">&#x27;9&#x27;</span>)</span><br><span class="line">		&#123;</span><br><span class="line">			c[p]=<span class="string">&#x27;0&#x27;</span>;</span><br><span class="line">			p--;</span><br><span class="line">			c[p]++;</span><br><span class="line">		&#125;</span><br><span class="line">		<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i&lt;=n;i++)</span><br><span class="line">		&#123;</span><br><span class="line">			u+=c[i]-<span class="string">&#x27;0&#x27;</span>;</span><br><span class="line">		&#125;</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">if</span>(c[<span class="number">0</span>]==<span class="string">&#x27;0&#x27;</span>) <span class="built_in">printf</span>(<span class="string">&quot;%s\n&quot;</span>,c+<span class="number">1</span>);</span><br><span class="line">	<span class="keyword">else</span> <span class="built_in">printf</span>(<span class="string">&quot;%s\n&quot;</span>,c);</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">int</span> T;</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;T);</span><br><span class="line">	<span class="keyword">while</span>(T--) <span class="built_in">work</span>();</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p><a target="_blank" rel="noopener" href="http://acm.hdu.edu.cn/showproblem.php?pid=4609">4609 3-idiots</a> 通过快速傅里叶变换求出所有可能的两条边构成的和的情况，然后排列组合枚举就好了 错误两次 第一次：数组开小了 第二次：有一个地方类型转换写错了，直接套的模板，模板是int</p>
<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;complex&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> N 540000</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> pi acos(-1)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="keyword">typedef</span> complex&lt;<span class="keyword">double</span>&gt; E;</span><br><span class="line"><span class="keyword">typedef</span> <span class="keyword">long</span> <span class="keyword">long</span> LL;</span><br><span class="line"><span class="keyword">int</span> n,m,L;</span><br><span class="line">LL R[N],c[N],sum[N];</span><br><span class="line">E a[N],b[N];</span><br><span class="line"><span class="keyword">int</span> p[N];</span><br><span class="line"><span class="keyword">int</span> u[N];</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">fft</span><span class="params">(E *a,<span class="keyword">int</span> f)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i&lt;n;i++)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">if</span>(i&lt;R[i]) <span class="built_in">swap</span>(a[i],a[R[i]]);</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i&lt;n;i&lt;&lt;=<span class="number">1</span>)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="function">E <span class="title">wn</span><span class="params">(cos(pi/i),f*sin(pi/i))</span></span>;</span><br><span class="line">        <span class="keyword">for</span>(<span class="keyword">int</span> j=<span class="number">0</span>;j&lt;n;j+=(i&lt;&lt;<span class="number">1</span>))</span><br><span class="line">        &#123;</span><br><span class="line">            <span class="function">E <span class="title">w</span><span class="params">(<span class="number">1</span>,<span class="number">0</span>)</span></span>;</span><br><span class="line">            <span class="keyword">for</span>(<span class="keyword">int</span> k=<span class="number">0</span>;k&lt;i;k++,w*=wn)</span><br><span class="line">            &#123;</span><br><span class="line">                E x=a[j+k],y=w*a[j+k+i];</span><br><span class="line">                a[j+k]=x+y;</span><br><span class="line">                a[j+k+i]=x-y;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">if</span>(f==<span class="number">-1</span>) <span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i&lt;n;i++) a[i]/=n;</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">work</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">int</span> q;</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;q);</span><br><span class="line">	q--;</span><br><span class="line">	<span class="built_in">memset</span>(c,<span class="number">0</span>,<span class="built_in"><span class="keyword">sizeof</span></span>(c));</span><br><span class="line">	<span class="built_in">memset</span>(p,<span class="number">0</span>,<span class="built_in"><span class="keyword">sizeof</span></span>(p));</span><br><span class="line">	<span class="built_in">memset</span>(a,<span class="number">0</span>,<span class="built_in"><span class="keyword">sizeof</span></span>(a));</span><br><span class="line">	<span class="built_in">memset</span>(b,<span class="number">0</span>,<span class="built_in"><span class="keyword">sizeof</span></span>(b));</span><br><span class="line">	<span class="built_in">memset</span>(R,<span class="number">0</span>,<span class="built_in"><span class="keyword">sizeof</span></span>(R));</span><br><span class="line">	n=<span class="number">0</span>;</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i&lt;=q;i++) &#123;<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;u[i]);p[u[i]]++;n=<span class="built_in">max</span>(n,u[i]);&#125;</span><br><span class="line">        <span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i&lt;=n;i++) &#123;a[i]=p[i];b[i]=p[i];&#125;</span><br><span class="line">	m=<span class="number">2</span>*n;</span><br><span class="line">	L=<span class="number">0</span>;</span><br><span class="line">	<span class="keyword">for</span>(n=<span class="number">1</span>;n&lt;=m;n&lt;&lt;=<span class="number">1</span>) L++;</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i&lt;n;i++)</span><br><span class="line">	&#123;</span><br><span class="line">		R[i]=(R[i&gt;&gt;<span class="number">1</span>]&gt;&gt;<span class="number">1</span>)|((i&amp;<span class="number">1</span>)&lt;&lt;(L<span class="number">-1</span>));</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="built_in">fft</span>(a,<span class="number">1</span>);</span><br><span class="line">	<span class="built_in">fft</span>(b,<span class="number">1</span>);</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i&lt;=n;i++)</span><br><span class="line">	&#123;</span><br><span class="line">		a[i]*=b[i];</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="built_in">fft</span>(a,<span class="number">-1</span>);</span><br><span class="line">	 <span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i&lt;=m;i++)</span><br><span class="line">	&#123;</span><br><span class="line">		c[i]=(<span class="keyword">long</span> <span class="keyword">long</span>)(a[i].<span class="built_in">real</span>()+<span class="number">0.1</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="built_in">sort</span>(u,u+q+<span class="number">1</span>);</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i&lt;=q;i++)</span><br><span class="line">	&#123;</span><br><span class="line">		c[u[i]+u[i]]--;</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i&lt;=m;i++) c[i]/=<span class="number">2</span>;</span><br><span class="line">	<span class="keyword">long</span> <span class="keyword">long</span> res=<span class="number">0</span>;</span><br><span class="line">	<span class="keyword">long</span> <span class="keyword">long</span> fz=(<span class="keyword">long</span> <span class="keyword">long</span>)(q+<span class="number">1</span>)*q*(q<span class="number">-1</span>)/<span class="number">6</span>;</span><br><span class="line">	sum[<span class="number">0</span>]=c[<span class="number">0</span>];</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i&lt;=m;i++)</span><br><span class="line">	&#123;</span><br><span class="line">		sum[i]=sum[i<span class="number">-1</span>]+c[i];</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i&lt;=q;i++)</span><br><span class="line">	&#123;</span><br><span class="line">		res+=sum[m]-sum[u[i]];</span><br><span class="line">		res-=(<span class="keyword">long</span> <span class="keyword">long</span>)(q-i)*i;</span><br><span class="line">		res-=q;</span><br><span class="line">		res-=(<span class="keyword">long</span> <span class="keyword">long</span>)(q-i)*(q-i<span class="number">-1</span>)/<span class="number">2</span>;</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">double</span> ans=res*<span class="number">1.0</span>/fz;</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;%.7lf\n&quot;</span>,ans);</span><br><span class="line">	<span class="keyword">return</span>;</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">int</span> T;</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;T);</span><br><span class="line">	<span class="keyword">while</span>(T--) <span class="built_in">work</span>();</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p><a target="_blank" rel="noopener" href="http://acm.hdu.edu.cn/showproblem.php?pid=4610">4610 Cards</a> 待补</p>

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